Soft X-ray generation after arc extinction of a low-current, repetitive discharge

Abstract

Summary form only given, as follows. Soft X-ray emission from a short vacuum gap, operated with repetitive low-current arc with peak current of 200 A and period of /spl sim/ 2 /spl mu/s was investigated. The repetitive discharge was generated by simply limiting the current from capacitor bank by a resistor. Point-like soft X-ray source was generated by using low bank voltage (/spl sim/ 20 kV) and short gap length (200 pm) to achieve small source size and high current density while preventing severe electrode damage. The electrode materials were copper, stainless steel of grade SUS304, silver and tungsten. Time-resolved soft X-ray intensity was monitored by a 2-channel filtered detector system composed of combination foil filters and fast, soft X-ray-sensitive scintillators and photo multipliers. The X-ray signals show that the most of X-ray radiation was emitted in period between arc extinction and subsequent breakdown, and that the X-ray intensity increased as the voltage between electrodes increased until the subsequent breakdown. The X-ray during this period was ascribed mainly to bombardment of anode by thermionic electrons that were emitted from high temperature region in the cathode surface, which is heated during arc phase.